A conventional thin film magnetic head is formed, as shown in FIGS. 12 and 18, by laminating on a non-magnetic substrate 3 a second magnetic material layer 2, a gap material 8, coil conductor layers 4, and a first magnetic material layer 1 which constitutes a pair of magnetic poles with the second magnetic material layer 2 in this order. Usually, in this kind of thin film magnetic head, the first magnetic material layer 1, the gap material 8, the coil conductor layer 4, and the second magnetic material layer 2 are all provided in planes parallel to the surface of the non-magnetic substrate 3, and the head is disposed so that it runs on a magnetic recording medium (not shown) in a direction perpendicular to the above planes for recording and reproducing. Such a thin film magnetic head inevitably suffers from the generation of a waveform distortion or false pulse which is caused by the thicknesses of first and second magnetic material layers 1 and 2, as shown in a solitary reproduced waveform diagram of FIG. 14. The waveform distortion occurs when a false gap parallel to the recording and reproducing gap of the magnetic head is formed in its surface area opposed to the magnetic recording medium 10. In the thin film magnetic head, in particular, since the thicknesses of the pair of magnetic poles formed by the first and second magnetic material layers 1 and 2 are approximate to the wavelength for recording, the false pulse by the false gap distorts the signal waveform reproduced from the true gap, impairing the reproduced signal quality.
A method that has been proposed for reducing the waveform distortion is disclosed in Japanese Patent Laid-Open Gazette No. 205508/87, for example. According to this method, the thickness of the first magnetic material layer 1 is varied widthwise of the magnetic track on the recording medium so that the bottom 9 of the first magnetic material layer on the opposite side from the gap material 8 is inclined thereto, as shown in FIG. 15. The magnetic head of this structure is capable of suppressing the generation of the false signal by the false gap and hence lessening its influence but is incapable of completely removing the waveform distortion. Further, the manufacture of such a magnetic head involves many machining steps such as the formation of a groove having a bottom inclined by an angle .theta. in the non-magnetic substrate 3, sputtering of the first magnetic material layer 1 on the substrate S, and subsequent lapping of its surface-this is not preferable as the thin film magnetic head manufacturing process. In addition, since it is difficult to improve the surface roughness of the bottom surface of the groove inclined by the angle .theta., there is a fear of providing poor magnetic characteristics of the first magnetic material layer 1.
Another prior art method proposed as a solution to the above problem is shown in FIG. 16, in which first and second magnetic material layers 1 and 2 on the non-magnetic substrate 3 are spaced apart in the direction A widthwise of the magnetic track (Japanese Patent Laid-Open Gazette No. 95713/87). This magnetic head structure is capable of eliminating the waveform distortion but encounters a problem of crosstalk from adjoining other tracks and overwrite thereinto which are caused by edge portions E of the second magnetic material layer 2 in the opposed surface area.